A gas chromatograph apparatus is an apparatus which feeds a gas sample into a column via a carrier gas, separates the respective components in the sample over time inside the column, and detects the components with a detector provided at the column outlet. Since the rates at which the respective components move into the column differ depending on the strengths of the interactions between the respective components in the sample and a stationary phase inside the column, the respective components are separated over time. At this time, the flow rate of the carrier gas is set to a rate within an optimal flow rate range at which the components in the sample can be sufficiently separated and at which peaks with sharp shapes can be obtained. In many gas chromatograph apparatuses, helium gas is used as a carrier gas due to a wide optimum flow rate range and high safety. Although inferior to helium gas from the perspective of safety, hydrogen gas is also sometimes used as a carrier gas due to a wide optimum flow rate range, as in the case of helium gas.
The rates at which the carrier gas or the respective components in the sample move into the column change due to the temperature or the like inside the column. Therefore, analysis cannot be performed accurately until these are stabilized. However, a long amount of time is required from when the power of the apparatus is turned on until the temperature or the like inside the column is stabilized at a prescribed value. Therefore, even if there is a certain amount of time after a given analysis is completed until the next analysis is performed, it is typical to maintain a standby state in which the temperature or the like inside the column is stabilized at a prescribed value in the same manner as at the time of analysis while the power is kept on. The carrier gas is circulated into the column even in the standby state. This is to prevent the stationary phase inside the column from degenerating due to water content or oxygen infiltrating from the outside or, conversely, to prevent the stationary phase from flowing out from the column outlet when the outlet side of the column is in a vacuum state, such as in the case of GC/MS, for example.
In this way, the column of a gas chromatograph apparatus is protected by circulating a carrier gas into the column even in the standby state. However, when the same amount of the carrier gas as at the time of measurement is circulated in the standby state, the running cost becomes high. In order to alleviate this problem, Patent Literature 1, for example, proposes a gas chromatograph apparatus which reduces the flow volume of carrier gas in the standby state.
PATENT LITERATURE 1—Japanese Unexamined Patent Application Publication 2000-304751
When the gas chromatograph apparatus described in Patent Literature 1 is used, the flow volume of the carrier gas in the standby state can be suppressed. However, even if the flow volume is suppressed, the amount of carrier gas consumption becomes large when the standby state continues for a long time. In particular, helium gas, which is used as the carrier gas of many gas chromatograph apparatuses, has become increasingly expensive in recent years, and there is a demand for a scheme to suppress the running cost of the apparatus.
The problem to be solved by the present invention is to provide a gas chromatograph apparatus and a gas chromatograph mass spectrometry apparatus capable of protecting a column at low cost in the standby state.